Alzheimer’s patients may be able to recover lost memories, according to a new study.

Researchers at the Massachusetts Institute of Technology, MIT, writing in the journal Nature, say that in the lab, mice with early stages of the degenerative brain disease form new memories. So do mice who are disease free, but are unable to recall things days later.

Using a technique called optogenetics, the researchers were able to coax those memories back.

The researchers say optogenetics is still not approved for use on humans.

“The important point is, this a proof of concept. That is, even if a memory seems to be gone, it is still there. It’s a matter of how to retrieve it,” said senior author Susumu Tonegawa from RIKEN-MIT Center for Neural Circuit Genetics.

He added that in the future, technology could be developed that could spur memory recovery in humans.

For the research, Tonegawa and his team placed mice in a chamber where they would receive a foot shock. All the mice “showed fear” when placed in the same chamber, but after several days, only the healthy mice still displayed fear. The mice with Alzheimer’s did not appear to remember the shock.

However, using flashes of blue light to stimulate the brain’s hippocampus region, the mice with Alzheimer’s appeared to remember the chamber and showed signs of fear.

According to the Huffington Post, this study builds on previous research that has shown that Alzheimer’s destroys synapses, but not necessarily memories.

“As long as the neurons are still alive, the memory will still be there, which means you may be able to recover some of the lost memories in the early stages of Alzheimer’s,” said researcher David Glanzman.